Microsoft IIS 5.0 improper authentication

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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A vulnerability, which was classified as critical, was found in Microsoft IIS 5.0 (Web Server). This affects an unknown code. The manipulation with an unknown input leads to a improper authentication vulnerability. CWE is classifying the issue as CWE-287. When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

The WebDAV extension in Microsoft Internet Information Services (IIS) 5.0 on Windows 2000 SP4 does not properly decode URLs, which allows remote attackers to bypass authentication, and possibly read or create files, via a crafted HTTP request, aka "IIS 5.0 WebDAV Authentication Bypass Vulnerability," a different vulnerability than CVE-2009-1535.

The bug was discovered 05/15/2009. The weakness was shared 06/10/2009 by Yamata Li (Website). The advisory is shared at This vulnerability is uniquely identified as CVE-2009-1122 since 03/25/2009. The exploitability is told to be difficult. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Neither technical details nor an exploit are publicly available.

It is declared as highly functional. The vulnerability was handled as a non-public zero-day exploit for at least 3400 days. During that time the estimated underground price was around $25k-$100k. The vulnerability scanner Nessus provides a plugin with the ID 39342 (MS09-020: Vulnerabilities in Internet Information Services (IIS) Could Allow Elevation of Privilege (970483)), which helps to determine the existence of the flaw in a target environment. It is assigned to the family Windows : Microsoft Bulletins and running in the context l. The commercial vulnerability scanner Qualys is able to test this issue with plugin 86837 (Internet Information Services (IIS) Could Allow Elevation of Privilege (MS09-020)).

Applying a patch is able to eliminate this problem. A possible mitigation has been published even before and not after the disclosure of the vulnerability. Furthermore it is possible to detect and prevent this kind of attack with TippingPoint and the filter 8221.

The vulnerability is also documented in the databases at X-Force (50768) and Tenable (39342).







CPE 2.3info

CPE 2.2info


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VulDB Meta Base Score: 8.1
VulDB Meta Temp Score: 7.7

VulDB Base Score: 8.1
VulDB Temp Score: 7.7
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Class: Improper authentication
CWE: CWE-287

Local: No
Remote: Yes

Availability: 🔍
Status: Highly functional
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Nessus ID: 39342
Nessus Name: MS09-020: Vulnerabilities in Internet Information Services (IIS) Could Allow Elevation of Privilege (970483)
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OpenVAS ID: 900567
OpenVAS Name: Microsoft IIS Security Bypass Vulnerability (970483)
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MetaSploit ID: dir_webdav_unicode_bypass.rb
MetaSploit Name: Web Site Crawler
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Threat Intelligenceinfo

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Recommended: Patch
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02/17/2000 🔍
03/25/2009 +3324 days 🔍
05/15/2009 +51 days 🔍
05/15/2009 +0 days 🔍
06/09/2009 +25 days 🔍
06/09/2009 +0 days 🔍
06/09/2009 +0 days 🔍
06/10/2009 +1 days 🔍
06/10/2009 +0 days 🔍
06/10/2009 +0 days 🔍
06/10/2009 +0 days 🔍
03/17/2015 +2106 days 🔍
08/11/2021 +2339 days 🔍



Researcher: Yamata Li
Status: Confirmed

CVE: CVE-2009-1122 (🔍)

X-Force: 50768
SecurityTracker: 1022358
Vulnerability Center: 22479 - [MS09-020] Microsoft IIS 5.0 on Windows 2000 WebDAV Remote Bypass Restrictions via HTTP Request, High
SecurityFocus: 35232 - Microsoft IIS 5.0 WebDAV Authentication Bypass Vulnerability
OSVDB: 56474 - CVE-2009-1122 - MS09-020 - Microsoft IIS - Authentication Bypass Issue
Vupen: ADV-2009-1539


Created: 03/17/2015 11:38 PM
Updated: 08/11/2021 03:46 PM
Changes: 03/17/2015 11:38 PM (86), 09/05/2019 07:02 PM (11), 08/11/2021 03:46 PM (3)
Complete: 🔍
Cache ID: 44:A32:40


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